package com.sunny.hp.common.util;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/********************************************************************************
 * <PRE> 암호화(AESDES)
 * 1. Project		: BEMS2.1
 * 2. Package	: com.ncomz.nzeip.common.util
 * 3. FileName	: EncryptUtil.java
 * 4. 작성자		: P044826
 * 5. 작성일		: 2013. 11. 20. 오후 2:50:39
 * 6. 설명			:
 * </PRE>
 ********************************************************************************/

public class EncryptUtil {
	
	private static final String CRYPTO_SEED_PASSWORD = "1234!@#$";   
	
	public EncryptUtil(){
		
	}
	public static String encrypt(String cleartext) throws Exception
	{
		byte[] rawKey = getRawKey(CRYPTO_SEED_PASSWORD.getBytes());
		byte[] result = encrypt(rawKey, cleartext.getBytes());
		return toHex(result);
	}
	
	public static String decrypt(String encrypted) throws Exception
	{
		byte[] rawKey = getRawKey(CRYPTO_SEED_PASSWORD.getBytes());
		byte[] enc = toByte(encrypted);
		byte[] result = decrypt(rawKey, enc);
		return new String(result);
	}

	private static byte[] getRawKey(byte[] seed) throws Exception
	{
		KeyGenerator kgen = KeyGenerator.getInstance("AES");
		SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
		sr.setSeed(seed);
	    kgen.init(128, sr); // 192 and 256 bits may not be available
	    SecretKey skey = kgen.generateKey();
	    byte[] raw = skey.getEncoded();
	    return raw;
	}

	
	private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception
	{
	    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
		Cipher cipher = Cipher.getInstance("AES");
	    cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
	    byte[] encrypted = cipher.doFinal(clear);
		return encrypted;
	}

	private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception
	{
	    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
		Cipher cipher = Cipher.getInstance("AES");
	    cipher.init(Cipher.DECRYPT_MODE, skeySpec);
	    byte[] decrypted = cipher.doFinal(encrypted);
		return decrypted;
	}

	public static String toHex(String txt)
	{
		return toHex(txt.getBytes());
	}
	
	public static String fromHex(String hex)
	{
		return new String(toByte(hex));
	}
	
	public static byte[] toByte(String hexString)
	{
		int len = hexString.length()/2;
		byte[] result = new byte[len];
		for (int i = 0; i < len; i++)
			result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
		return result;
	}

	public static String toHex(byte[] buf)
	{
		if (buf == null)
			return "";
		StringBuffer result = new StringBuffer(2*buf.length);
		for (int i = 0; i < buf.length; i++) {
			appendHex(result, buf[i]);
		}
		return result.toString();
	}
	
	private final static String HEX = "0123456789ABCDEF";
	private static void appendHex(StringBuffer sb, byte b)
	{
		sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
	}

	/**
	 * @param args
	 * @throws Exception 
	 */
	public static void main(String[] args) throws Exception {
		// TODO Auto-generated method stub
		String passwdAES = "";
		passwdAES = EncryptUtil.encrypt("1");
		System.out.println(passwdAES);
		System.out.println(EncryptUtil.decrypt("D3F313AD7D6DD78AC32528D852E6FECB"));
	}

}
